I often meet a condition in programming where I have a class which takes an instance of another class and makes use of some functions in that imported class, while that class also needs some functions in the first class.

Like class A has function x() and y(), and class B has function i() and j(). Class A needs to use function i() in class B, and function j() in class B needs to use function y() in class A.

How can I reduce this to minimum? Is there any better way to do this? For some reasons, function y is only available in class A.

Well my first thought is that since the two classes seem to need each other so closely - and are apparently unable to function without each other - surely they should be merged somehow? In most designs classes do not interact mutually but only in one direction, but I suppose there are situations where you can end up with circular dependencies.

What is your exact situation?

The slowsort algorithm is a perfect illustration of the multiply and surrender paradigm, which is perhaps the single most important paradigm in the development of reluctant algorithms. The basic multiply and surrender strategy consists in replacing the problem at hand by two or more subproblems, each slightly simpler than the original, and continue multiplying subproblems and subsubproblems recursively in this fashion as long as possible. At some point the subproblems will all become so simple that their solution can no longer be postponed, and we will have to surrender. Experience shows that, in most cases, by the time this point is reached the total work will be substantially higher than what could have been wasted by a more direct approach.

Well my first thought is that since the two classes seem to need each other so closely - and are apparently unable to function without each other - surely they should be merged somehow? In most designs classes do not interact mutually but only in one direction, but I suppose there are situations where you can end up with circular dependencies.

What is your exact situation?

Thanks for the reply, Bacterius.

So there's a protocol class which has a function to write data to the socket. This protocol class needs a function from another class and it sends some data to the said class. Still in one direction, right. Then this another class has a function which process the data sent by the protocol, and after processing the data it needs to write data to the socket. This is where things go circular.

I don't really got you point. As @Bacterius said, you can easily merge A and B.
Another way, you can define a pure virtual base class X which has function x(), y(), i(), j(). So that A or B inherit from X, so they can used them without any trouble. all right?

I don't really got you point. As @Bacterius said, you can easily merge A and B.
Another way, you can define a pure virtual base class X which has function x(), y(), i(), j(). So that A or B inherit from X, so they can used them without any trouble. all right?

How about I make a subclass of the protocol class so I can inherit the write function? Is it a bad idea? Merging both function may make some of my things to work nastily, so I won't do that unless I can find another way.

According to your situation, why do you seperate those function base on their responsibility. I would like to define the protocolClass as a virtual class so that it could provide a processData() method, it no need to worry about the write and send function. SocketBuffer will take care of that.

According to your situation, why do you seperate those function base on their responsibility. I would like to define the protocolClass as a virtual class so that it could provide a processData() method, it no need to worry about the write and send function. SocketBuffer will take care of that.

Actually I've solved this by subclass-ing the protocol class. The subclass inherits all of the functions the protocol class provides, and I can define the service specific functions in that subclass to make everything neat and stuff.